Take the inputs out of the amp and turn the amp on. If you have no hum, the hum is coming from elsewhere. If you have many grounded units, you will typically get a ground loop or hum. This is caused by two or more routes to ground with differing potential. Unground the preamp and reconnect it to the amp with no cheater plug on its power cord. If you have no hum, go with it. Otherwise, unground other source units. Although many go with only the preamp grounded, you probably would feel more comfortable with only the amp grounded. |
If you ground the amp as Gregadd suggests to the wall receptacle, you will have the same ground loop. Ground only the amp to a real ground will not cause the ground loop. |
Nothing would be harmed. My guess is that it would sound better. |
If he has two paths to ground with different resistance to ground, he has a ground loop. The cheater opens one of these paths, closing it again by attaching the wire of the cheater to the ground at the outlet reconnects it. I must admit that I am merely restating what I said as I have no idea what you don't understand in my posts. |
Rex, you statistic cause alarm, but we would need to know how many of these fires come from electric space heaters. This is all a red herring considering the original question about hum. |
Household appliance including mainly portible heating devices?
Again you exaggerate, even if in caps. Many audio and video devices with three pin wall plugs have no connection in the device of the grounding wire. All cd players that I have checked, both of the preamps I have, and the phono stages lack any chassis ground. The primary reason is gound loop problems.
How precisely would you cope with ground loops, oh superior one?
It is circuit breakers that are the primary electrical protection. It would be really stupid to put a penny into the fuse box as people used to do before breakers. |
This gives a good explanation of what the problem is and why it exists, but it is mainly for AV systems. It does suggest starting with the amp only in the system. You will probably not have much hum. Then you add until you get hum. Guess what you then deal with the problem, which probably means ungrounding that component.
It also suggest plugging everything into one power strip. This is in effect star grounding and will usually cause no problems. |
"STUPID, STUPID" Your statement prompted my dismissal of your condecenson. One of my undergraduate majors was EE, so don't lecture me.
None of the component that I refer to have plastic housings, so forget that assumption.
"if (the grounding of the chassis) is removed and there is a ground fault" (and if the person is grounded, there can be a fatal shock. Really? Lots of ifs, which many manufacturers ignore.
Shorts or hot wires cause electrical fires. Don't breakers deal with shorts?
Given your fear of electricity, you probably should use a 12 volt system.
I see no reason to continue this tangent off the original question. |
You are right, I am a very prideful guy. I am off to lick my wounds. LOL. |
They are; this is why you get ground loops. Sometimes, however, the chassis is not grounded to neutral or to anything. |
Ldatlof, yes I am surprised that Rex even has electricity in his house. |
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All depends on whether the plug going into the Sirius is at 12 volts or 120 volts. I have no idea. It takes about 32 volts for current to flow through your body, so a 12 volt wire under no circumstances can hurt you. If the body of the Sirius is non-conductive, again unless you put a wire into it while standing in water on a concrete floor, you again will be beyond danger. If it is 120 volts presented to the Sirius, it has a metal body, you are grounded, and somehow the case is charged at 120 volts, you could be in danger. Incidentally, if you use a cheater plug and ground it grounding wire to the outlet, your circuit breaker would immediately open in the event of a charged body of the Sirius.
Rex strikes me a unduly concerned about the grounding wire to components. Underwriters Labs insists on grounded components with metal bodies, but few major manufacturers of front end audio components bother to ground their chasses, because of the ground loop problem thus introduced. |
Rex, On your question #1 please bear in mind that most Japanese products come with three prong plugs but few have the ground attached to anything. Many don't even have a third, ground connector at the unit.
Artar,
I recommend the following procedure to at least identify the culprit.
1. disconnect everything except the amp to speaker wires. Put shorting plugs into your main amp and turn it on. If you have no hum, the culprit is not the amp.
2. Connect the preamp to the amp after removing the shorting plugs. Turn the preamp on and then the amp. If you have no hum, neither are culprits.
3. Plug in one front end device. If you have no hum, with it active, it is not the culprit.
4. When you add something that causes hum, it is the culprit. It is possible that it is that unit's interconnects, so try others. Also it may be the only grounded front end device. Try a cheater plug. If the hum does not go away, try reversing the cheater. If none of this works, you have a problem with that device.
If the hum goes away with the cheater, which will typically be the case, you have an issue--do you need it grounded? Rex would answer one way and I another.
You might also find that grounding the unit to the amp may cause the hum to go away. Also a resister on the ground may solve the problem. |
